For nearly two weeks, the nation has been transfixed by wildfire spreading through Yosemite National Park, threatening to pollute San Francisco's water supply and destroy some of America's most cherished landscapes. As terrible as the Rim Fire seems, though, the question of its long-term effects, and whether in some ways it could actually be ecologically beneficial, is a complicated one. Some parts of Yosemite may be radically altered, entering entire new ecological states. Yet others may be restored to historical conditions that prevailed for for thousands of years from the last Ice Age's end until the 19th century.